In the Comparison mode (see Comparison of two Trace Files), the Filtering dialog has an additional label and a combo box that enables you to apply the chosen filter expression to the other trace file shown in the View.

In the combo box, choose the

If expression is valid in other file

option to check if the resulting expression is valid in the name space of the other file. If so, the filter applies the expression as if you had manually typed it in the other file filter dialog box. Any previous input in the target dialog box is overwritten.